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June 2006
SPECIAL REPORT:Undercounter Warewashers Take the TestBy Brian Ward

Turn on
the tube, read a newspaper or just stare at your utility
bills. Energy and water costs are up and rising. How much? A
lot of places that paid 7 or 8 cents a kilowatt hour five
years ago now pay 10 or 11. Natural gas that used to cost 60
cents a therm in 2001, is widely over a dollar now. In
California? More like 13 to 15 cents a kWh and north of
$1.25 a therm.

All of
which has caused a lot of activity. The Environmental
Protection Agency’s Energy Star programs now extend to
foodservice reach-ins, fryers, hot holding cabinets and
steamers. The California Energy Commission is setting
requirements for more categories of equipment every year.
ASTM Int’l. currently has standardized test methods on the
books for more than 30 categories of foodservice equipment.

Utilities
are now such a big deal for operators, in fact, that the
National Restaurant Association’s annual survey of concerns
now puts energy at the top of the list. When has that ever
happened before? Never.

With all
this in the background, we figured it was a good time to
take a hard look at warewashers. As a category, they’re
huge users of utilities, gulping water and the energy to
heat it in vast quantities, not to mention the load they
create for direct ventilation and HVAC systems. We wondered
how warewasher makers were responding to the new cost
pressures

So we
went where we always go for such projects, Pacific Gas &
Electric’s Food Service Technology Center in San Ramon,
Calif. We pitched Don Fisher, of Fisher-Nickel Inc., the
consulting firm that operates the FSTC. Could the FSTC team
help us set up a group bench test? For that matter, could
the FSTC invent such a test, considering no standardized
warewasher test for utility efficiency yet existed? Never
one to pass up an interesting experiment, Fisher took about
two seconds to say yes. Todd Bell would run the program,
assisted by Dave Zabrowski.

Undercounters would be the category, we all agreed. Several
new, more efficient models were hitting the market, and
besides, undercounters were much easier to ship to the lab
than, say, 44” conveyors. In the end, four manufacturers
jumped on the opportunity to get third-party data in a new
kind of test.

Starting
Where NSF Leaves Off

NSF
Int’l. had already tested the units to certify they
delivered the proper amount of energy to the rinse water and
the dish for a proper 180°F sterilizing rinse, so the FSTC
didn’t need to reinvent that wheel. And unlike most ASTM
test methods born at the FSTC, this one wouldn’t measure
throughput, again because NSF has its own such measurements.

The focus
here, instead, would be on a kind of typical usage, and the
costs involved with gas, electricity and water consumption.
Determining exactly what to measure, and how, was an
exhausting process. Scores of details had to be considered
and second- and triple-guessed.

Without
wearing you out with the minutiae, the test would delve into
preheat time, preheat energy, idle energy rate, wash energy
rate, wash cycle time and water consumption in gallons per
rack and total. The gas heat for the building’s central
water supply, which delivered 140°F water, would be
included. With some estimates of typical usage in the field,
annualized costs could be projected.

The test
method itself began with providing 140°F supply water from
the building’s gas heater, which produced said water at a
rate of about 142 gals./therm. Then came preheating each
warewasher and “running one empty rack through the
factory-set wash cycle to stabilize the wash compartment
temperature,” project engineer Todd Bell said. “After the
empty rack was removed and the water tank heating elements
had cycled off, the first rack of plates was loaded.”

Racks
were 20” x 20” peg types, each loaded with 10 clean plates,
9” glazed ceramics weighing 1.3 lbs. each, give or take less
than an ounce. Each rack was run through the full wash
cycle, with four minutes between each rack for typical
loading, unloading usage. In all, 10 racks would be washed
in each set. After the last rack was removed, and the wash
tank heating elements cycled off, indicating the
thermostat’s set temp was restored, time, energy and water
consumption were measured. For each washer tested, the
process was repeated three times to assure reliable data. In
addition, idle-test data were collected over three-hour idle
periods.

A 40%
Spread

And the
results? All four undercounters handily outperformed
comparable units from just a few years ago. The bar chart in
this story clearly shows the overall cost data. Model A
costs about 10% less in water and energy than its nearest
competitor. And Model D brings up the rear, fully 41% more
expensive than the pack-leading Model A and nearly 27% more
costly than the third-place finisher.

But as
always, digging a little deeper reveals more interesting
bits—more interesting in the sense that there’s much to be
learned about how different designs have different strengths
and weaknesses.

Water
Matters

At the
risk of saying what seems obvious, water consumption is a
critical design focus. Yes, it matters because water and
sewer charges are shooting upward like so many Roman
candles. In fact, a look at the chart will show you how
water costs in this test compared to the gas costs for
preheating the incoming water—the water costs are more than
60% as high as the gas bills.

But the
more important reason water consumption matters is that it
drives the gas and electrical usage. More water per rack
means more gas for preheating and more electricity for
pumping and in-tank heating. The particulars vary depending
on local utility rates, of course, but the correlations are
important everywhere.

Tank Heat
Costs Money

What’s
glaringly apparent in this test is that tank heat is
mucho expensive, and you want to pay attention when
you’re specifying warewashers. In the test scenario,
electrical costs consistently account for more than twice as
much as gas plus water combined. That means
electrical runs 65% to 70% of the total utility bill for
these diminutive units. In some parts of the country, like
in the Southeast, for example, where electricity is
relatively cheap, the ratios will be different. But even
there, the juice will run as much or slightly more than gas
and water combined.

Accordingly, it appears the engineers at three of the four
manufacturers have done their level best to optimize
electrical efficiency. Model C manages to heat 3.67 gals.
per kWh, while Model B’s close at 3.22. Then the overall
champ comes in third at 2.88 gals. per kWh. All in all, a
fairly competitive spread.

But the
big surprise—make that disappointment—in this test was Model
D’s electrical usage. Put plainly, it wasn’t in the same
league. How could the water-sippingest washer in the bunch
use so much electricity? Testers suspect a reservoir that
was larger and shallower than the others’. That meant it had
more surface area for its volume, more surface for heat
loss. That, combined with smaller heaters, led to a cycle
time that was virtually endless. If the engineers take a
second look at that part of the design, they should be in
good shape. The water and gas data are already class
winners.

Annual
Projections—Your Mileage May Vary

After the
data were collected, the team had to decide how to turn the
whole works into annual consumption rates. Out in the field,
hours of operation range all over the board, so it’s hard to
pinpoint a profile.

For
projection purposes, the FSTC decided to assume a longish
day, 18 hours, knowing full well that many operators would
adjust that assumption but needing some standardized
starting point. These undercounters typically are used in
not-so-high volume applications, so the group settled on 75
racks per day (roughly four per hour) as a round guesstimate
for test purposes.

And idle
time? Most undercounters are left on in between runs, some
only sporadically and some all day long. This projection
would assume the units are turned on and left on. The whole
works would then be multiplied by 360 workdays in a year.

All of
which means your mileage may vary, but at least you can see
the component data and adjust your own assumptions. In this
test format, for example, a lot of idle time is involved,
which is why Model D’s high idle rate is such a killer.
Idling at 1.2 kW, it’s sucking more than 2.5 times as much
energy as the closest competitor’s 0.44 kW rate.

Conversely, if your washer doesn’t spend all day idling,
water-per-rack is the big priority, in which case Model D
moves to the top slot by a clear margin.

Eventually, Bell says, the FSTC will probably put some kind
of warewasher calculator up at
www.fishnick.com to go with the ones already there for
fryers, ovens and steamers, so you can plug in your own
variables and make your own calculations. But for now, you
can do it the old-fashioned way—with a hand-held calculator
and a pencil.